A gas turbine engine, typically used as a source of propulsion in aircraft, operates by drawing in ambient air, combusting that air with a fuel, and then forcing the exhaust from the combustion process out of the engine. A fan and a compressor, such as a dual-spool compressor, rotate to draw in and compress the ambient air. The compressed air is then forced into the combustor, where a portion of the air is used to cool the combustor, while the rest is mixed with a fuel and ignited.
Typically, an igniter generates an electrical spark to ignite the air-fuel mixture. The products of the combustion and the remains of the air-fuel mixture then travel out of the combustor through a turbine as exhaust. The turbine, also a dual-spool configuration, is forced to rotate by the exhaust. The turbine, the compressor, and the fan are connected by an engine shaft, and in this case of a dual-spool configuration a pair of concentrically mounted engine shafts, running through the center of the engine. Thus, as the turbine rotates from the exhaust, the fan and the compressor rotate to bring in and compress new air. Once started, it can thereby be seen that this process is self-sustaining.
Combustors for gas turbine engines typically have a shell and a liner with an air passage defined therebetween. In an annular combustor an outer liner and an inner liner cooperate to define an annular combustion chamber between the inner and outer liners. In such a combustor, there is at least one igniter for igniting the air-fuel mixture. In some combustor designs, the liners may be segmented into panels.
The combustor further has a combustor bulkhead at a front end of the chamber extending from the outer shell to the inner shell. At least one fuel injector extends through this combustor bulkhead and into the combustion chamber to release the fuel. A swirler is generally positioned around each fuel injector to create turbulence in the combustion chamber and mix the combustion air and the fuel before the mixture is combusted.
In prior art designs, the swirler, including a housing and vanes, has a circular projection, that is, all radii of the swirler are equal. While effective, this circular projection may not adequately mix the air and the fuel in all situations, which may create difficulties in achieving the balance of emission, operability, and durability of the combustor and turbine. The round circular nature of the swirler may create further difficulties when utilized with annular combustors. Thus, a new swirler design is needed to achieve better mixing of the air and fuel, particularly with an annular combustor.